Materials of high strength and super heat resistance have recently been desired in various industrial fields. Among such materials are alumina fibers which are suitable for use in fabrication of composite materials in combination with metals, ceramics and so forth.
A method of calcining fiber precursors made of organoaluminum polymers has received increasing attention for the production of superior alumina fibers. However, a method has not been developed yet which produces with ease and further with high efficiency high molecular weight organoaluminum polymers which are suitable for use in production of such fiber precursors. That is although it is known that organoaluminum polymers can be prepared by reacting organoaluminum compounds with water, high molecular weight organoaluminum polymers suitable for use in preparing, e.g., fibers are difficult to produce by conventional procedures.